Preserving Quality After Heavy Compression of DV Footage

[taigi]

I'm concerned about the significant file size reduction after processing my DV footage with QTGMC, filters and a CRF of 12. The original bitrate was 24.4 Mb/s, and after processing, it's down to 6,616 kb/s.

I'm unsure if keeping the processed file is sufficient. Can't believe. Some other files with darker footage resulted in even lower bitrates after processing.

I'd appreciate any advice on the best approach to handle this situation.

Thanks.

MediaInfo:
ORIGINAL:
General

Format : AVI
Format/Info : Audio Video Interleave
Commercial name : DV
Format profile : OpenDML
Format settings : BitmapInfoHeader / WaveFormatEx
File size : 5.30 GiB
Duration : 24 min 57 s
Overall bit rate mode : Constant
Overall bit rate : 30.4 Mb/s
Frame rate : 25.000 FPS
Recorded date : 2014-11-21 18:52:44.000
TAPE : Tape 1
TCOD : 17861200000
TCDO : 32835600000
VMAJ : 4
VMIN : 0
STAT : 37436 0 3.433874 1
DTIM : 30410172 1434265088

Video
ID : 0
Format : DV
Codec ID : dvsd
Codec ID/Hint : Sony
Duration : 24 min 57 s
Bit rate mode : Constant
Bit rate : 24.4 Mb/s
Width : 720 pixels
Height : 576 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 FPS
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Bottom Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 2.357
Time code of first frame : 00:29:46:03
Time code source : Subcode time code
Stream size : 5.02 GiB (95%)

MODIFIED:
General
Format : AVI
Format/Info : Audio Video Interleave
Format settings : BitmapInfoHeader / PcmWaveformat
File size : 1.42 GiB
Duration : 24 min 57 s
Overall bit rate : 8 172 kb/s
Frame rate : 50.000 FPS
Writing library : VirtualDub2 build 44282/release

Video
ID : 0
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L5
Format settings : CABAC / 16 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 16 frames
Codec ID : H264
Duration : 24 min 57 s
Bit rate : 6 616 kb/s
Width : 1 024 pixels
Height : 576 pixels
Display aspect ratio : 16:9
Frame rate : 50.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.224
Stream size : 1.15 GiB (81%)
Writing library : x264 core 157 r2935M 545de2f
Encoding settings : cabac=1 / ref=16 / deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=10 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=24 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=6 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=8 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=crf / mbtree=1 / crf=12.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Color range : Limited
Matrix coefficients : BT.470 System B/G

[Sharc]

Nothing to worry about. The reduction is reasonable, crf 12 is on the safe side. You may even try crf 16 and compare.
(Lossless would be crf 0 by the way).

The DV is 25Mbit/s (constant bitrate) by the DVCAM standard because it is a (simple) on-the-fly (real time) compression.

I'd be more concerned about playback device compatibility (e.g. your TV) of your encode with 16 ref frames and 8 bframes.

[Bernix]

I think playback on TV or DVD players with H264 support will be problematic anyway. Because x264 VFW in AVI container as final compression is IMHO not best today. Maybe used to be 10 years ago. I believe there are many pro users having rich experience with x264vfw. Who can tell you more about pros and cons, and in better English then I can. I can be completely wrong.

[taigi]

x264 VFW in AVI container as final compression is IMHO not best today.

Could you suggest a more effective format, please?

[jagabo]

Virtually nothing outside a Windows computer will play h.264 video in an AVI container. The OP should use MP4 or MKV for h.264 if he wants wide compatibility.

With x264 and a good preset CRF 12 is visually lossless for most material, even when A/B flipping enlarged still frames. Around CRF 18 is visually lossless when watching most material at normal playback speed. Use something like that for material you are going to view outside a PC.

DV always uses the same bitrate, regardless of the material. If a frame after DCT compression doesn't deliver enough bits it is padded with junk to increase its size so the resulting compressed frame is always the same size (roughly 1 Mb for PAL DV). For example, an all black frame could be compressed down to almost nothing. But it will occupy about 1 Mb on tape and in the resulting AVI file. Most of that 1 Mb will be padding.

The OP should always save the original DV AVI. You never know when better deinterlacing, denoising, upscaling, and compression options will become available in the future. Going back to the original source will always give you the best results.

[Alwyn]

H264 or AVC is normally stored in the MP4 container with AAC audio (in this scenario). This will give you the best compatibility across all devices/screens.

DV isn't a very efficient compression method compared to H264/AVC, so that's why DV file sizes are much larger than the equivalent-quality H264 file sizes.

Into the bargain, processed DV, especially lower-light DV, can be markedly improved with noise-reduction software such as various filters in AVISynth and the paid Neat Video plugin for various programs.

So, your H264 movies will look at least as good as your DV files, if not better, particularly if you apply some noise reduction.

As mentioned, CRF 12 is a good setting for exporting H264 from DV. The lower the CRF, the better the quality. Or if you are into using bitrates, 5000kb/sec will give you great-looking MP4s from DV.

[Bernix]

As said, better is normal x264 in mp4 or mkv. Not VFW version. For avi is "native" for example xvid video with mp3 sound. Or some lossless codecs, but they are good for intermediate work.
How efficient is DV compression you can see that your 5GB original file can be probably cut down in size by many percent 20%? just 7zip it.


There are more efficient codecs, but x264 is efficient enough